致命错误：意外发现nil，同时隐式展开Optional值

Question

致命错误：在隐式展开一个可选值时意外地发现nil

let title = "Submit Confirmation?"
let message = "Do you want to submit?  "
let popup = PopupDialog(title: title, message: message, image: UIImage(), buttonAlignment: .horizontal, transitionStyle: .zoomIn, preferredWidth: (self.view.bounds.width - 20), tapGestureDismissal: true, panGestureDismissal: true, hideStatusBar: false, completion: nil)
let btnCancel = CancelButton(title: "Record Again"){
   popup.dismiss()
   self.movieOutput.startRecording(to: self.fileUrl, recordingDelegate: self)
   self.startTimer()
   let delayTime = (DispatchTime.now() + 60)
   DispatchQueue.main.asyncAfter(deadline: delayTime){
      Toast.init(text: "Recording start again").show()
      self.movieOutput.stopRecording()
      self.stopTimer()
   }
}